Innovative Tools for Molecular and Cell Biology

Innovative Tools for Molecular and Cell Biology


Reagents for Molecular Biology

IPTG and X-Gal



  • IPTG (i-Propyl-ß-D-ThioGalactoPyranoside) is utilized for the induction of expression from the lac-promoter and derivates. IPTG is an inducer of galactosidase activity in many bacteria. Functioning as an analog, IPTG induces galactosidase activity by binding to and thus inhibiting the repressor. IPTG is used to differentiate recombinants from non-recombinants in cloning strategies using vectors containing the Z or Z peptide gene.

  • Dissolve IPTG in water at 200 mg/ml. Sterilize solution through a 0.2 µm filter, dispense in small aliquots, and store at -20 °C. Use at a final concentration of 250-350 µg/mL in top agar and liquid cultures. Specific applications may require more or less IPTG. Isopropyl-ß-D-thiogalactoside is analytical grade material, free of dioxane.


  • 5-Bromo-4-chloro-3-indolyl ß-D-galactopyranoside is most commonly known as X-gal. X-gal is a histochemical substrate for ß-galactosidase which cleaves X-gal to yield an insoluble blue precipitate.
  • X-gal is a mainstay in molecular biology cloning applications in which it is used to detect the activity of ß-galactosidase. X-gal is used to detect the insertion of foreign DNA into the lacZ region of a plasmid DNA. Insertion of DNA into the lacZ region results in the loss of ß-galactosidase activity.
  • X-gal is used to indicate whether a cell expresses the ß-glactosidase enzyme, which is encoded by the lacZ gene, in a technique called blue/white screening. Bacterial cells that retain active ß-galactosidase will result in characteristic blue colonies. Successful disruption of the lacZa gene disrupts the α-complementation of the ß-galactosidase gene and the precipitate does not form, resulting in white colonies.

  • For detailed information (specification, SDS, CofA, etc.) on IPTG and X-gal, please click on the corresponding PDF link in the order table.


  • For shipping and storage information please click on Order#.
Order# Description Amount Price Data Sheet
I1312-1gAG IPTG 1 g 22,00 PDF
I1312-5gAG IPTG 5 g 27,00 PDF
I1312-25gAG IPTG 25 g 119,00 PDF
I1312-50gAG IPTG 50 g 191,00 PDF
I1312-100gAG IPTG 100 g 369,00 PDF
X1015-1gAG X-GAL 1 g 52,00 PDF
  • All prices are in EURO excl. VAT and shipping. Only available in Germany and selected European countries.